In electrohydraulic control systems for aircraft or the like, a variable output pump such as a variable displacement pump is coupled through control valves and actuators or motors to operate aircraft mechanisms, such as the landing gear, etc. The pump may comprise a hydraulically controlled pump coupled by an electrohydraulic servo valve to an electronic pump controller which receives command signals from a remote or master controller responsive to the aircraft pilot for controlling the pump flow to the various loads as required for aircraft operation. One or more sensors are coupled to the pump for sensing operation and providing feedback signals to the pump controller, such that the controller effectively closes a servo loop for operation of the pump.
An object of the present invention is to provide an electrohydraulic control system of the described character which possesses enhanced versatility and accuracy, both in terms of response stability and response time, than do control systems of a similar nature in the prior art, which exhibits an enhanced operating range, which is inexpensive and reliable in long term operation, and/or which is capable of self-diagnostics for identification of potential system failures. Another object of the present invention is to provide an electrohydraulic control system of the described character which finds particular utility in aircraft applications, which possesses reduced size as compared with prior art systems, which features fail-safe operation, and/or which reduces power dissipation and heat loss.